题解 | #统计每个用户的平均刷题数#
统计每个用户的平均刷题数
https://www.nowcoder.com/practice/f4714f7529404679b7f8909c96299ac4
select university,difficult_level, count(qpd.device_id)/count(distinct qpd.device_id) as avg_answer_cnt from question_practice_detail qpd left join question_detail qd on qpd.question_id =qd.question_id left join user_profile up on qpd.device_id = up.device_id group by university,difficult_level having university='山东大学'
